This invention relates to a polyglutarimide molding material reinforced by carbon fibers.
Polyglutarimide which is a non-crystalline resin with high transparency is used as molding materials and recently, being used as a core material for plastic optical fibers. The heat resistance of polyglutarimide is remarkably improved due to its structure of glutarimide ring so that the heat distortion temperature exceeds 150.degree. C. in case of using polyglutarimide as a molding material. However, such a polyglutarimide, originally, falls under the category of acrylic resins and therefore, does not have satisfactory properties in respect of tensile strength, tensile modulus, flexural strength, flexural modulus and impact strength.
As for carbon fiber reinforced plastics, for example, a carbon fiber reinforced polyester resin, the shrinkage in volume is caused by the plastic deformation and crystallization when cooled after heat molding and therefore, the resulting molded product has a remarkable distortion so that its commercial value is extremely reduced.
Also, in case of a carbon fiber reinforced polyamide resin, the crystallization velocity is larger than the abovementioned polyester resin so that the distortion during molding further increases. Under the existing circumstances, carbon fiber reinforced materials of crystalline resins are almost reduced unavoidably in the commercial value due to the distortion during molding.